Broken Crank Shaft
Discussion
Oh no !!!!!! 
My 1996 4.2L AJP has just suffered from a broken Crank shaft. What now?????
I can see Powerperformance have 22weeks lead time. Is there anywhere else I can get a new (or 2nd hand) one?
Is it simple to change it (has anyone made a guide how to)? I was warned that since my engine is old then a new crank shaft may not fit without modification of the engine. Can any one confirm if that is true?
Alternatively, I could change the engine, preferable with a 4.5L. Do any of you know were I can find another engine?
Sad regards
My 1996 4.2L AJP has just suffered from a broken Crank shaft. What now?????
I can see Powerperformance have 22weeks lead time. Is there anywhere else I can get a new (or 2nd hand) one?
Is it simple to change it (has anyone made a guide how to)? I was warned that since my engine is old then a new crank shaft may not fit without modification of the engine. Can any one confirm if that is true?
Alternatively, I could change the engine, preferable with a 4.5L. Do any of you know were I can find another engine?
Sad regards
darreni said:
Mine went in 2003 & i had the car shipped back to the factory. They fitted a 4.5 crank & a load of engine work. It was with them for a month & the parts cost was just shy of 10k.
Yes, the though has come to me but the price is +10K and for the price I might be able to find "new" engine and the use the old for spares.How did yours?
CerbWill said:
Thomas, its engine rebuild time I'm afraid.The engine needs to come out and the sump removed to remove the broken crankshaft. I'd bet any engine builder would want to strip it completely to ensure any small bits of the crankshaft are removed so they dont cause damage later. Later engines use a crankshaft with 2.5" diameter main bearings, whereas your engine has an early crankshaft with 2.3" diameter journals. Whats interesting is that it's very rare (unheard of even?) for the later crankshafts to snap, but the early type never snapped at the journals. When it comes to putting the engine back together you could use a small journal crankshaft if you could find one but it might snap again, or you line bore the block and fit a later crankshaft. I do have an early crankshaft removed from my engine when it was rebuilt but its sat rusting for a couple of years now. It may be beyond usable, I don't know. I upgraded to the later crankshaft because I could afford a new crank a lot more than I could afford a 2nd engine rebuild!
Why did you get the engine rebuild if the crankshaft was intact? Do you have any photos of the small journals crankshaft you have and is it up for adoption ? 
Jhonno said:
As it is a '96 I suspect you had one of the early small journal cranks, which are a ticking time bomb by all accounts. Especially with TVR tolerances on balancing..
There was a later small journal crank which as far as I am aware, doesn't tend to break unless you get a bad casting..
There was also a billet small journal, then the later cast large journal.
Could be worth seeing if anyone would make you a billet small journal crank using your current one as a basis. Save you having to line bore.
The small/large journal has nothing to do with strength, TVR changed over when Rover did as it runs RV8 bearings. It was just the earlier small journal crank which either had not enough counterweight, or poor castings.
As you point out the problem is finding a crankshaft. Has anyone any suggestion where I can get one? I live abroad, which make things even more complicated when owning a TVR There was a later small journal crank which as far as I am aware, doesn't tend to break unless you get a bad casting..
There was also a billet small journal, then the later cast large journal.
Could be worth seeing if anyone would make you a billet small journal crank using your current one as a basis. Save you having to line bore.
The small/large journal has nothing to do with strength, TVR changed over when Rover did as it runs RV8 bearings. It was just the earlier small journal crank which either had not enough counterweight, or poor castings.
I have looked around, but none of the local workshops are capable of making a new crankshaft based on the old. Do you know of any specialist in UK who would be able to do so? Jhonno said:
As it is a '96 I suspect you had one of the early small journal cranks, which are a ticking time bomb by all accounts. Especially with TVR tolerances on balancing..
Do you know what the tolerances should be, if I can find someone to make a new crankshaft based on the old one?CerbWill said:
As I was spending a fair bit of money at that point it seemed a shame that I wouldnt get any more power out of it, so I went all in and went for the 4.7 upgrade.
How much power did you gain from this conversion? Did you also get a new ECU or is it running on the factory fitted one? How much did you spend on this upgrade?
CerbWill said:
Speculating that Thomas' intent is a quick fix to get a summer's motoring in I think 'patching it up' with a small journal crank is risky and will take a significant amount of time to achieve. Given his location listed location is Denmark unless he's very handy with the spanners and has some engine building experience it might be time to consider crating the engine up and sending it to Powers Performance or APM.
Thomas, who has diagnosed a snapped crank, what state is the engine in now? It could (but hopefully hasnt) damaged the block so just putting another crank in may not even be possible. You won't know until the engine is in bits, unless there's a rod through the block!
Thomas, who has diagnosed a snapped crank, what state is the engine in now? It could (but hopefully hasnt) damaged the block so just putting another crank in may not even be possible. You won't know until the engine is in bits, unless there's a rod through the block!
The car has been diagnosed by my local garage. It has not been totally dismantled so there is the risk that the block is damaged. A least we have not seen any signs of this.
Is the exhaust, the engine harness and the ECU the same for the 4.5 and 4.7 ? (ie. can I just box up the engine, get it rebuild and then fit it back in without doing any other modifications?)
Edited by thomas.moeller on Wednesday 9th June 13:49
gruffalo said:
Yep, not sure it is achievable, I have thrown lots of cash at it but not completely sure it is achievable.
500 would be nice but I do feel it would be willy waving. Any time other than summer I have to be careful not to get carried away with the right foot even in 3rd on the motorway, I have had some huge power slides at 80 in 3rd on a dry but cool road even with top grade tyres.
550Hp : https://www.pistonheads.com/gassing/topic.asp?h=0&... but don't believe all you read 500 would be nice but I do feel it would be willy waving. Any time other than summer I have to be careful not to get carried away with the right foot even in 3rd on the motorway, I have had some huge power slides at 80 in 3rd on a dry but cool road even with top grade tyres.
MattPlaneCrank said:
So Thomas are you going for the 4.7 conversion? Powers seem very busy at the moment, my car is there having a new clutch and a few other bits done and they have a backlog of work so if you send your engine there it won’t be quick!
Also what sort of real 0-60 does 400+BHP give you?
My first option is still to get an upgrade, but as you point out Powers and Str8Six are very busy and it is difficult to convince them to do a pre-2000 engine. I was advised to try to contact Simon Wood. I think he is with Lotus now, but I have not been able to get hold of him. I don't have his email address, so if any has it, please share it as a private message. Also what sort of real 0-60 does 400+BHP give you?
If anyone got any "strings" to pull or could put in a word for me at either Powers or Str8Six I would be grateful.
Who else do the 4.7 Conversion?
Alternatively, I'm looking into a rebuild if I can get parts and finally there is the option to buy another engine. The last one seem to be a rather expensive option since I would have to import it in to EU which will add 10% customs duty + 25% VAT.
Another problem is getting the Engine to UK. I spoken to more than 10 companies and so far none of them will go to UK after Brexit. Too much paperwork and waiting time they say.
It seems like I finally manage to find someone willing to take the job
I was recommended to go for the 4.5 red rose conversion instead of the 4.7. Apparently, the 4.7 got more torque at low revs, but the 4.5 revs up faster (does that make sense?)
Could it be that the 4.5 is more agile and gives you a faster car in the middle range? Do anyone got any first hand experience?
My son use to do a lot of karting and here it was not always the engine with most BHP being the fastest on the a narrow track
I was recommended to go for the 4.5 red rose conversion instead of the 4.7. Apparently, the 4.7 got more torque at low revs, but the 4.5 revs up faster (does that make sense?)
Could it be that the 4.5 is more agile and gives you a faster car in the middle range? Do anyone got any first hand experience?
My son use to do a lot of karting and here it was not always the engine with most BHP being the fastest on the a narrow track
Hi all,
Too much work and too little time to do the important things...... like getting the engine out of my cerb
I have been advised to take the engine out with the gearbox attached. Do any of you clever people know how to remove the gear lever. It looks like it is connected to the gearbox with two bolts but they are hard to get to and I'm in doubt if it is easier to remove them from the top (inside the car) or from underneath the car. Do any of you have a clever trick?
Have a great day
Too much work and too little time to do the important things...... like getting the engine out of my cerb
I have been advised to take the engine out with the gearbox attached. Do any of you clever people know how to remove the gear lever. It looks like it is connected to the gearbox with two bolts but they are hard to get to and I'm in doubt if it is easier to remove them from the top (inside the car) or from underneath the car. Do any of you have a clever trick?
Have a great day
CerbWill said:
Undo the 4x 13mm bolts that hold the gear selector plate onto the gearbox. I use a 1/4" drive ratchet, its fairly easy.
Great, thanks for a quick respond - Edit** I get at those bolts from under the car reaching up to the top of the gearbox.
Edited by CerbWill on Thursday 22 July 21:35
Gassing Station | Cerbera | Top of Page | What's New | My Stuff